The present invention concerns a vehicle and a method for controlling the stability against tipping of the vehicle according to the description herein.
The vehicle can be of any type that is intended for a use in which the risk of the vehicle tipping over exists and therefore an arrangement to determine the position of the vehicle's tipping point is necessary. It will be apparent that the invention is specially intended for vehicles equipped with lifting units to lift loads, which can substantially displace the vehicle's tipping point by having significant weight and/or displacement relative to the vehicle's own centre of gravity. The invention is therefore particularly related to industrial trucks, and such, for lifting and transporting loads, mainly at industrial sites, warehouses or loading yards. It is however even possible that the risk of the vehicle tipping over is dependent on the fact that it driven over uneven ground, which can displace the vehicle's tipping point outside the stability area.
In order to illustrate the invention, but not in any way to limit the invention, a vehicle in the form of an industrial truck will mainly be described hereafter.
The reason why a vehicle is provided with a frame part that is pivotable relative to the chassis in this way around a so-called swing axle is that the vehicle can thereby move over uneven ground in a significantly more comfortable way than if the frame part was locked relative to the chassis since, because of this, the vehicle will not lean as much to the side as would otherwise be the case.
However this means that the vehicle's stability area, i.e. the area, defined in the horizontal plane, within which the vehicle's centre of gravity has to be located so that the vehicle will not tip, more particularly a triangle defined by both of the wheels located on the first side and the swing axis' point on the other side, becomes smaller. In order to prevent the vehicle from overturning in situations which it would have managed in the case of fixing the frame part relative to the chassis it is known to arrange said means for locking the frame part relative to the chassis on the orders of the arrangement. However when this takes place one refrains from the advantages that pivoting possibilities around the swing axle entail. If the vehicle's tipping point is later displaced further towards the stability area's boundary an emergency stop will eventually be required, which prevents the vehicle from carrying out manoeuvres other than those that bring the tipping point nearer to the centre of the stability area.